Security doors and the like and in particular revolving-type security doors are designed to limit access to a certain area or room of a building or structure to only authorized personnel. For example, in the private sector, it is desirable to limit access to authorized personnel to computer rooms where confidential or vital business or personal information and data is retained in the computer memory. Unauthorized access may result in the theft or destruction of that information and data. Similarly, restricted areas such as those areas wherein research and development are being conducted, where trade secret equipment, processes or information is retained, or where valuable materials or equipment are located also requires means to limit access to only authorized personnel. Not only would unlimited access jeopardize the information and equipment as far as theft and destruction is concerned, but also may present a public crisis should terrorist gain access to those areas.
In nuclear facilities, strict security is required to protect fissionable material from theft by terrorists or the like. Security may also be required to control access to areas monitoring and operating equipment which, if damaged or destroyed, may present a danger to a large segment of the public.
In a public sector, government facilities may contain top secret information, equipment or restricted material or confidential or otherwise vital information which, if in the hands of unauthorized personnel such as terrorists, may jeopardize national security or otherwise endanger the public. As can be appreciated, tight security under these and other circumstances is of extreme importance.
Accordingly, there is a present need for a security door, and in particular, a revolving security door adapted to restrict access to the security areas or rooms to only authorized personnel. Heretofore, the only means to restrict access has been to use security guards posted at the entrances and exists of the security area. Guards present are additional expense and may not be reliable.
In an effort to dispense with the need for personnel posted at the security area, some elementary forms of security systems involving revolving doors have been developed. One type is found in U.S. Pat. No. 4,341,165, issued July 27, 1982 to Calandritti et al. However, this type of revolving door is only adapted to prevent access to those carrying weapons and the like as sensed by a metal detector, and does not attempt to completely prevent access by unauthorized personnel.
In another type of revolving door, U.S. Pat. No. 4,295,297, issued Oct. 20, 1981 to Carroll et al, the revolving door is adapted to only prevent reverse movement or travel of a person from one area to another. The revolving security door does not attempt to restrict access to, for example, a security room, but only to prevent unauthorized exit. Accordingly, this type of revolving door is only concerned with controlling the direction of movement of personnel rather than restricting access.
As can be appreciated, none of the prior art focuses upon a revolving security door and controls therefore to limit access and exit to and from a security area to only authorized personnel. In particular, none of the revolving doors found in the prior art address the major problems faced when designing a revolving security door and controls to limit access and exit to and from a security area. One major problem, hereinafter referred to as piggy-backing, is where an unauthorized person attempts to accompany an authorized person, in the same compartment, through the revolving door. Revolving doors heretofore found in the prior art have been unable to recognize and prevent such a mode of unauthorized access. Another problem hereinafter referred to as "pass back", is that of where an authorized person, as recognized by the door control system, for example by a card key or the like, passes back the card key to an unauthorized individual who uses the same card to gain entrance. Still another problem is that of preventing simultaneous travel of an unauthorized person from, for example, the door entrance into the security area as an authorized person moves with the door from the security area to return to the door entrance. Yet another problem not addressed in the prior art, over and above the recognition of authorized personnel and the various modes of unauthorized entry noted above, is the return of the unauthorized person to his or her point of entry into the door.